Precise coordination of the S and M phases of the eukaryotic cell cycle is critical not only for normal cell division, but also for effective growth arrest under conditions of stress. When damaged, a cell must communicate signals to both the mitotic and DNA synthesis machineries so that a mitotic block is not followed by an extra S phase, or vice versa. The biochemical mechanisms regulating this coordination, termed checkpoints, have been identified in lower eukaryotes, but are largely unknown in mammalian cells1-3.
DNA-damaging agents are used in the clinic to preferentially kill cancer cells. However, there is a need in the art to discover additional therapeutic agents which are selectively toxic to cancer cells.
It is an object of the invention to provide methods for screening for anti-cancer drugs.
It is another object of the invention to provide cell lines useful for screening for anti-cancer drugs.
These and other objects of the invention are provided by one or more of the embodiments described below. In one embodiment of the invention, a method for screening test compounds to identify those which are potential anti-tumor agents is provided. The method comprises the steps of: determining DNA content of checkpoint gene-defective human cells incubated in the presence and in the absence of a test compound, wherein a test compound which causes DNA accumulation in the checkpoint gene-defective cell is identified as a potential anti-tumor agent.
In another embodiment of the invention, a different method of screening for potential anti-tumor agents is provided. The method comprises the steps of: determining viability or apoptosis of checkpoint gene-defective human cells incubated in the presence and in the absence of a test compound; selecting a test compound which causes cell death or apoptosis in the checkpoint gene-defective cell.
In yet another embodiment of the invention a homozygous checkpoint gene-defective human cell line is provided.
In still another embodiment of the invention a pair of isogenic cell lines is provided. The first cell line is a homozygous checkpoint gene-defective human cell line and the second cell line is a homozygous checkpoint gene-normal human cell line.
These and other embodiments of the invention provide the art with new methods and cell lines for screening potential anti-tumor agents.